The present invention is directed to a display device which includes a light valve display or unit arranged in conjunction with a fluorescent plate which is a plate-like body containing fluorescent particles and having at least one exit window for the fluorescent light.
Displays, which utilize a light valve unit having at least one zone, which is switchable in its optical state, and a fluorescent plate comprising a plate-like body containing a fluorescent material and having at least one exit window aligned with the switchable zone are described as "fluorescent activated displays" (FLAD) and have been described in various publications, for example, in an article in Electronics, Dec. 8, 1977, pp. 113-116 or as described in German Offenlegungsschrift 25 54 226, whose disclosure was included in U.S. patent application Ser. No. 747,035 filed Dec. 2, 1976, which issued on Mar. 6, 1979 as U.S. Pat. No. 4,142,781.
Within the scope of the FLAD development, problems have occurred on how the light valves can be positioned and fixed in an adjusted position relative to the fluorescent plate. On occasion, the alignment process necessary for this purpose is extremely time consuming as the display zones of the light valves, which are determined by the virtually invisible electrode segments, must be aligned with the associated light outlet or exit windows of the fluorescent plate at the rear and often no reference lines are available. The cost for adjustment, which cost has hitherto been expended in producing the devices, is no longer acceptable particularly when an FLAD device is to be produced on a large scale or in mass production.